This Phase II proposal seeks to address an unmet need for mechanical circulatory support in children with heart failure. Pediatric heart patients possess several unique features, such as small body size, reduced blood volume, and altered hemodynamic properties, which distinguish them from adults with heart failure. We have sought to account for these features by developing a miniature, low-cost, centrifugal ventricular assist device for use as an extracorporeal mechanical support system. Our approach features a magnetically levitated, and thus friction-less, rotor/stator configuration, which efficiently generates flow, with minimum hemolysis. The major advantages of the current design are its small and relatively simple extracorporeal design, its ability to efficiently regulate pump output over a large range of flow conditions, and its ease of production. In Phase I testing, Levitronix, in collaboration with the University of Pittsburgh, demonstrated the soundness of this technology for the pediatric application through a series of successful in vitro and in vivo experiments. In Phase II we intend to complete the design and validation of the product, and to launch device readiness testing in anticipation of clinical trials. We contend that the development of a small, inexpensive pump, which requires a minimal priming volume, and which eliminates seals and bearings, is highly desirable. The specific aims of this proposal are: 1) To optimize pump and cannulae design to meet the cardiac support requirements of children. 2) To refine the design of the drive console for pediatric operating conditions. 3) Conduct reliability testing of motors, pumps, and drive consoles. 4) Demonstrate hemodynamic performance and biocompatibility in vivo. We believe that our technology, which provides effective left ventricular assistance with a small, disposable device, will provide needed benefits to the health of children with severe cardiac disease, while not adding significantly to cost of caring for these patients. Achieving the aims proposed in this Phase II program will validate the safety and suitability of the Levitronix pediatric ventricular assist device for evaluation under an IDE clinical trial, which will be carried out in a Phase III program. We project that in Phase III of the project, we will meet the regulatory requirements governing an IDE, fabricate verified and validated hardware, establish reliability, and conduct indicated clinical trials.